a. Field of Invention
The present invention relates to an oral hygiene device comprising a stem brush, on a holder of an electric toothbrush. More specifically, the invention relates to an automatic insertion system for assuring the proper orientation and mounting of the stem brush on the holder.
b. Description of the Prior Art
Automatic stem brush insertion systems for oral hygiene devices have been proposed. For example, French Patent No. 2,276,015 discloses a stem brush with an automatic insertion system wherein the brush stem is snapped on a cylindrical shaft having a transverse pin. A helical ramp forms part of a resilient snapping system of the brush stem. It has been found that the holding force of the brush stem decreases rapidly because the snapping system is rapidly worn out after a relatively few insertions. The requirement that the pin of the motor shaft has to be in metal adds significantly to the cost of the oral hygiene device.